Reinforcement element and method of producing a reinforcement element

ABSTRACT

Procedure for fabrication of reinforcement elements for concrete, where an extended, preferably continuously fibre bundle ( 10 ), especially of carbon fibres, impregnates ( 3 ) by a matrix of a plastic material followed by curing. The fibre bundle ( 10 ), including a significant amount of single fibres, is brought after impregnation ( 3 ) and prior to curing ( 17 ) to cooperate with a particle shaped material ( 15 ), preferably sand, as adhere to the fibre bundle surface mainly without coming in between the fibres and fixate to the surface by curing, for creation of a reinforcement element.

This invention states a reinforcement element for concrete and a methodhow to fabricate such a reinforcement element. The element is of thekind that includes an extended, preferably continuously bundle offibres, especially carbon fibres, impregnated, witch a plastic basedmatrix wish is cured.

Use of traditional reinforcement of concrete, it is known to use steelrebar with profiled surface with the intention to increase the bondtowards the concrete as example a ribbed bar. Such ribbed reinforcementbars can also be used as mesh and other reinforcing structures dependingon what shall be produced or build in reinforced concrete. It is alsoknown to use reinforcement elements or mesh based on non-metallicmaterials, especially elements based on fibres, also including carbonfibres. Also this type of reinforcement elements has been subjected forribbed or similar surface treatment with the intention to ensure aproper adhesion when embedded in concrete.

Example on previous known executions can be found in U.S. Pat. No.5,362,542 and U.S. Pat. No. 6,060,163 and Japanese patent publications020.484.45A, 040.596.42A, 031.502.41A, 031.502.42A, 032.958.38A,020.484.44A, 021.924.44A, 030.838.40A, and 010.189.50A.

In the light of the known technology, the present invention takes thestarting point in a method where an extended preferably continuousbundle of fibres, especially carbon fibres, impregnates with a matrixbased on a plastic material followed by curing.

The invention does it possible to achieve a better performance ofreinforcement materials or mesh where the surface structure gives a veryfavourable foundation and adhesion in concrete being caste around, inaddition as the fabrication of such elements can take place in a simpleand effective manner to low cost. This to be achieved by assistance ofthe new and characteristic feature in accordance to the invention, asdescribed in the patent claims.

The invention shall in the following be explained closer by referring tothe drawings, where:

FIG. 1 schematic show the first step in the production of a fibre bundlewith impregnation of a plastic material,

FIG. 2 likewise show the first step in accordance to the invention, fortreatment of the fibre bundle from FIG. 1, to a more or less finishedproduct in form of a treated reinforcement element,

FIG. 3 show an alternative performance compared to the one in FIG. 2,namely for production of a continuously and flexible reinforcementelement, as example as a band,

FIG. 4 show another alternative performance, where the reinforcementelement is utilized to fabricate a dedicated reinforcement structure, asexample with focus to pillar reinforcement, angular reinforcement orsimilar,

FIG. 5 show very elevated an example on a cross section of a fibrebundle and a coated reinforcement element in accordance to theinvention.

FIG. 6 illustrates schematic the fabrication of a reinforcement netbased on the method in accordance to the invention,

FIG. 7 show in relation to FIG. 6, a slight simplified fabrication,namely with focus on pole type of reinforcement elements,

FIG. 8 show another modified performance from the one in FIG. 6, forfabrication of a reinforcement mesh where the elements are crossing withvariable angular, and

FIG. 9 show the cross section and elevated construction of crossingpoint of a reinforcement mesh from FIG. 6, possibly also FIG. 8.

In the first part of the fabrication line, as illustrated on FIG. 1, alarge number of continuous single fibres or filaments 1 are pulled orsupplied in a large number from the same amount of stock or spools R1and brought gather down in a container with a bath of liquid plasticmaterial or matrix 3 for impregnation. Appropriate the gather fibrebundle is lead in the bath 3 by assistance from rollers, as examplemarked R2 and R3. Over the roller R4 the impregnated fibre bundle isguided out of the bath, possibly by giving a pretension, which can takeplace by assistance from a pulling device 5 including double rollers,also acting to press out additional uncured plastic materials the fibrebundle is impregnated with. From there, the fibre bundle 10 is guidedfurther to the following fabrication steps, with focus on fabrication ofa continuous pole type reinforcement element, possibly a flexible bandor equal or reinforcement mesh, respectively a tree dimensionalreinforcement structure. Also twinning of the fibre bundle can be ofinterest.

In conjunction to FIG. 1, it shall be pinpointed that the inventionassume a significant number of single fibres 1 in the compound fibrebundle 10, where the number of fibres shall be in the magnitude of 1000or may be up to 10,000,000 or more. In praxis this is total realisticbecause the fibre diameter typical can be 7 microns. In the bath 3 theliquid plastic is thermo set or eventually thermo plastic. Examples forsuitable plastic materials are polyester, vinyl ester, and epoxymaterials. When the fibres or filaments 1 are impregnated for followingcomposite association with each other, the high number single fibreswill have great importance. The increasing number of fibres andincreasing fibre bundle dimension, the relative surface towards thesurrounding environment is reduced. The surplus of the matrix or plasticmaterial being applied, as partly will remain adhered on the outside ofthe fibre bundle, can vary depending of different temperatures andviscosities of the plastic material. Here a significant amount ofvariation possibilities is present with focus how to decide the requiredamount of plastic cover outside the composite fibre bundle, minding therequired properties, as adhesion- or shear capacities after embedded inconcrete. When it comes to viscosity (after Brookfield, test inaccordance to ASTM D 2196-86), this may be in the range of 100-1000mPas(cP), which mainly will cover the actual alternative matrixmaterials.

In the following fabrication steps as illustrated on FIG. 2 (and FIG. 3)the impregnated fibre bundle 10, while the impregnation material stillis mostly uncured and near the liquid phase, is guided to cooperationwith a particle shaped material 15 located in box type container 12. Inthe bottom of the box 12 there are organized nozzles or holes 13 asappropriate with its cross section form gives the fibre bundle requestedcross section profile. When the fibre bundle 10 from the hole 13 passthrew the reservoir of particle shaped material 15, as in accordance tothe invention primarily is sand, the particles will adhere to thesurface of the fibre bundle, and then be permanent rooted or fixated tothe surface of the fibre bundle by curing in zone 17. By assistance froma pulling device with rollers 18 the finished reinforcement elementbrought to a cutting- and packing station not illustrated in FIG. 2.There is an essential feature with the fabrication as illustrated onFIG. 2, that the particle shaped material such as sand, adhere to thesurface of the fibre bundle 10 mainly without coming in between thefibres. This is a great benefit because potential sharp particlespotentially could penetrate into the cross section of the fibre bundlein between the single fibres, will potentially damage the fibres in thisfabrication stage or potentially under following static or dynamicforces as the fibres will suffer, as in a cured reinforced concrete. Asan example on cross section geometries that the hole 13 can give thefibre bundle 10, a circular or rectangular shape is near buy, but it isclear that cross section geometries can free be chosen depending on theuse for the reinforcement element.

In conjunction for the above mentioned parameters in the fabricationsteps in accordance to FIG. 1 and FIG. 2, it calls here that afabrication temperature or curing temperature in the zone or device 17,can be in the range of 15-40° C., based on the most common curingsystems. This is also with the thought for a potential manual placing orhandling for fabrication of special reinforcement structures at laterfabrication steps.

By use of sand as particle shaped material the grade can appropriate bein the range of 100 microns to 5000 microns particle diameter. Togetherwith the previous parameters for the matrix material and so on, suchsand will give an advantages adhesion to or shear capacity between thefibre bundle and the surrounding caste concrete. This allows an optimalutilization of the special fabricated composite fibre bundle. For use inconcrete optimal shear capacity is 1-50 Mpa.

The fabrication steps in accordance to FIG. 3 segregates from theexecution in accordance to FIG. 2 by that the finished reinforcementelement winds up as a coil on a drum 19 also acting as a pulling deviceto pull the reinforcement element threw the curing device 17 and tostore the finished product, as in this case presuming to have sufficientflexibility or bend ability, achieved by suitable choice of thementioned parameters and materials as entering in the fabrication.

The arrangement in FIG. 4 have the most steps like the illustration onFIG. 2 and 3, but here it is arranged a rotateable mould body 29 as thereinforcement material winds up on under the continues fabricationprocess. First of all the body 29 also serves pulling the reinforcementelement from the previous fabrication step, and secondly the crosssection of the body 29 and the guides of the reinforcement materials onthis is adjusted so that the desired configuration is achieved. As anexample, this can be a prefabricated reinforcement structure for aconcrete pillars. It can be imagined a large number of variations suchas cross section geometry of the mould body 29, with focus on decidedcross section or configuration of the reinforcement. Some of the crosssection variations are shown on FIG. 4 by A, B, C, D and E.

A fibre bundle is shown as a cross section and strongly elevated at FIG.5. The left halve of this figure shows a fibre bundle of filaments 30where the impregnation material or matrix is applied, where the plasticmaterial has penetrated in to the fibre bundle cross section and filledthe voids in between the single fibres 30, and the outer surface 31Amainly constitute this coating of the plastic material. This conditionas illustrated on the left side of FIG. 5 correspond to the fabricationstep ahead of applying of the particles, for example in form of sand,the cross section will be as shown on the right side of FIG. 5. Theshown particles 33 can have wide range of shapes and sizes, but asillustrated on FIG. 5 the particles can be considered to be drawn somedecreased compared to the dimensions of the fibre bundle inside.Furthermore it is clear that the previous described curing of thereinforcement element result in a fixed foundation of the particles 33in the surface layer 31A of the curable plastic material 31. Forfabrication of reinforcement elements as reinforcement mesh or equal itis in accordance to the invention suggested performance as first of allschematic is illustrated on FIG. 6. There it is shown a under layersurface or support 20 with the requested horizontal extent, for examplewith a couple metres side edge in a rectangular form adjusted to whatkind of construction to be reinforced, such as a slab in a building.Along the edge of a supporting surface 20 it is shown a lot of guidanceelements 1-8 as for example sticks or a spike organized in a predictedmanner. It is also possible to organize (not shown) edge- or wallsegments some elevated, compared to the supporting surface 20 along theedges, however not as elevated as the guiding elements 1-8.

Based on an organization just described, a mesh geometry reinforcementgeometry be fabricated by that a fibre 10, coming from the previousfabrication step in accordance to FIG. 1, be guided mechanically ormanually between the guiding elements 1-8 for creation of a mesh forexample with small rectangular meshes. This takes place while theimpregnation of the fibre bundle still is not cured. The winding orguidance of the reinforcement element 10 can take place multiple or inseveral turns, so that it more or less layer on layer creates areinforcement grid with a dedicated thickness of the individual straightparts of the fibre bundle creating the mesh.

The completed reinforcement grid is on FIG. 6 as a whole identified 28.

While the impregnation material still is sticky, it is then suppliedwith particle shaped material as indicated by 25, with other wordspreferable from above by suitable sprinkling or equal, so that thismaterial can adhere to the fibre bundle over all and simultaneously becollected at the supporting surface 20. The collection of the particleshaped material on this surface can possibly take place to such athickness or height that the surface touches the fibre bundle in thereinforcement grid 28 resulting in a more intimate contact and adhesion.This collection of the particles can also be performed in advance priorto location of the fibre bundle, especially for good cover on the lowerside of the fibre bundles.

After such a covering of the fibre bundle(s) they remain strapped untilcuring of the plastic material has taken place. This can for exampletake place by providing heat in an appropriate manner. Thereby theparticle material get fixated to the surface of the fibre bundles asexplained in connection to FIGS. 2 and 3 above.

Prior to or after removing the finished coated reinforcement mesh 20,from the guiding elements on the supporting surface 20, it can beconvenient to remove the sand or particle material, by advantage thiscan take place by openings 26 in the supporting surface 20. At thislocation, 4 positions 26 is shown, however in practices a larger numbercan be beneficial, as potentially can be closable. Suitable remedy1O forsuch removal of leftover particle material can be taken into action.

On FIG. 6 a crossing point 22 is marked in the reinforcement mesh, and agreat enlargement such crossing point 22 is shown in the cross sectionon FIG. 9. In the crossing layer of the fibre bundles there the uppercross section of the fibre bundle 10A is shown, as mainly is a bandshape with a certain plain pressure, rectangular cross section profile.Under the fibre bundle 10A it is also shown altering crossing fibrebundles totally eight layers in this shown example for a crossing point22. The connection in the crossing point will in this way be verypowerful, in high degree because of the impregnation and the followingcuring. Further more, it is of impotence in this connection thatprovided particle shaped material or sand (at position 25 on FIG. 6) notwill have the tendency to penetrate in between the layers in thecrossing point 22. Consequently it is also here avoided that destructivepollutions or sharp particles can enter inn and harm the fibres in thecrossing points.

Now it refer to FIG. 8 as show a modification of the mesh pattern inaccordance to FIG. 6, namely by that the provided fibre bundle 10 isguided in a more or less irregular and diagonal angular to creation of areinforcement mesh with variations of the mesh geometry, namelybasically a non rectangular mesh.

This can be advantages for some applications. Also here it is pinpointed at a crossing point, namely as indicated at 32, where the layerconstruction can take place totally analogue with that illustrated onFIG. 9.

Finally FIG. 7 show a utilization of the supporting surface 20 includingguiding elements 1-7 for fabrication of straight length reinforcementelements, namely with lengths close to the length between edge of thesurface 20 supplied with the guidance elements 1-7. After completedwinding as the situation is described on FIG. 7, with the followingapplying of the particle formed material followed by curing, eachindividual straight length reinforcement element cut loose by cuttingalong line 39A and 39B as indicated on FIG. 7. This execution can betaken as an alternative to the more continues fabrication in accordanceto the illustration on FIG. 2. A modification of the method inaccordance to FIG. 7 can be to neglect to cut the elements, by that thewhole structure is lifted up from the supporting surface and is bendedor straight out to create of a longer, continues reinforcing element.

Considering providing with particle formed material, furtheralternatives than described above are present. Another alternative is toguide the fibre bundle threw a cyclone or equal where it maintain aswirl or “sky” of air and sand or other particle material.

It can be realized based on the description above that until curing ofthe impregnation or matrix material takes place, can the fibre bundles,or reinforcement elements, eventually the reinforcement grid orstructure in three dimensions, be given near all different shapes fromthe simple straight poles or bands to more complicated configurations asdescribed. In all cases it will be achieved a very favourable geometryfor reinforcement elements wile embedded in concrete gives very goodadhesion or anchoring as wanted. This get achieved in spite of very lowinvestments in fabrication equipment and with limited need for energyconsumption heating.

1-10. (cancelled)
 11. Method for fabrication of a reinforcement element(19, 28) for concrete, where an extended, preferably a continuous fiberbundle (10), especially of carbon, is impregnated (3) with a matrixbased on plastic followed by curing, characterized in that the fiberbundle (10), which includes a very large number of single fibers atminimum in the order of magnitude of 1.000, after impregnation (3) andprior to curing (17) is brought to cooperate with a particle shapedmaterial (15, 25), preferably sand, by pulling up through holes (13) inthe bottom of a container (12) containing the particle shaped material(15), which is adhered to the surface of the fiber bundle mainly withoutcoming in between the fibers and are fixed to the surface by the curing,for creation of a reinforcement element (19, 28).
 12. Method accordingto claim 11, wherein the required cross-sectional shape of the fiberbundle (10) is obtained by means of correspondingly shaped holes (13).13. Method according to claim 12, wherein the fiber bundle (10) ispulled from the container (12) by being wound up on a rotating mouldbody (29) the cross-sectional shape of which is adapted to give aresulting reinforcement element with a desired configuration. 14.Reinforcement-element for concrete, including an extended, preferably acontinuous fiber bundle, especially based on carbon, impregnated with amatrix based on plastics being cured, characterized in that the fiberbundle surface, including a significant number of single fiber atminimum in the order of magnitude of 1.000, is coated with a particleshaped material, preferable sand, which is adhered to the fiber bundlewith the cured plastic material.